The present invention relates to a projectile used for incapacitation of a human being or animal target and more specifically mechanisms for absorbing kinetic energy of the non-lethal projectile.
Conventional weapons are used by law enforcement personnel to deter and subdue criminals. However, the use of conventional weapons by the law enforcement personnel is limited by the possibility of inflicting injury to an alleged suspect, since the courts and not law enforcement personnel have the responsibility for determining guilt and sentencing a criminal. Even worse the use of conventional weapons by law enforcement personnel may lead to a tragic injury or death of an innocent bystander. Furthermore, non-lethal weapons are required for controlling crowds in violent demonstrations.
A non-lethal weapons system is used to incapacitate as opposed to inflict injury in order to prevent suspect targets from fleeing, engaging in further combat, or committing other criminal acts. Conventional non-lethal weapons include billy clubs (or batons) rubber and plastic bullets. Batons as used by the law enforcement officers are wielded in close range and are capable of inflicting serious physical trauma. Rubber and plastic bullets are typically too energetic to be used at distances less than about 25 meters and become ineffective at distances greater than 50 meters. Conventional rubber and plastic bullets have caused a significant number of unwanted injuries.
U.S. Pat. No. 3,710,720 discloses a weapon system including a launcher and a flexible low lethality projectile of relatively large mass adapted to be radially expanded during trajectory so as to present a relatively large impact surface to the target. The projectile has an initial relatively small cross section so as to be insertable in a conventional launcher. The launcher has internal rifling grooves within the barrel to effect rotation of the projectile and radial expansion thereof due to centrifugal force. The relatively large area of contact on impact reduces energy per unit area penetration of the target while maintaining high inertia energy.
U.S. Pat. No. 6,012,295 discloses a baton projectile including a case of low density polyethylene, and a core of a soft material such as a thermoplastic gel modified rubber. At higher than acceptable impact forces, the case ruptures and the core spreads out to radially disperse the excess impact energy and to present a larger impact area to the target so that the risk of unacceptable penetration and trauma injury to the target is reduced.
The term “target” as used herein refer to the person or animal being incapacitated. The term “outward” as used herein referring to a non-lethal projectile includes a direction with a significant radial component pointing away from the longitudinal axis of the projectile.
The term “viscoelasticity” as used herein describes materials that exhibit both viscous and elastic characteristics when undergoing deformation.
The term “energy density” as used herein refers to a kinetic energy impact of a projectile on a target and is defined as the kinetic energy of the projectile divided by the area of the impact, typically given in units of area per square centimeter.
The term “pressure” as used herein refers to the force of impact of a projectile on a target divided by the area of the impact.